(a) Field of the Invention
The present invention relates to soft unpolished rice and a method of preparing the same and, more particularly, to soft unpolished rice which has abundant nutritive substances, enables easy water-permeation, has good texture, and is easily digested.
(b) Description of the Related Art
The general rice grain (1) is shown in FIG. 1. As shown in FIG. 1, a most outer shell or hull (2), of the rice grain (1) is a fibrous cell including lignine and SiO.sub.2, and is resistant to humidity, heat and cold. Under the hull (2), rice bran is formed. The rice bran is a hard, dense thin layer, and has hydrophobic properties. The rice bran includes pericarp (3), testa (4) and an aleurone layer (5). The rice grain (1) further includes an embryo (6) and an endosperm (7) having starch. It is from the embryo (6) that a new shoot or roots sprout.
Unpolished rice is prepared by removing the hull (2) from the rice grain (1), while polished rice is prepared by removing the hull (2) and the rice bran, and in some instance, even the embryo. The nutrient compositions of unpolished rice and polished rice are shown in Table 1. As shown in Table 1, the unpolished rice is rich in nutrients such as protein, lipid and mineral, more so than polished rice.
TABLE 1 [per 100 g] Nutrients Unpolished rice Polished rice 1 Protein 7.2 g 6.5 g 2 Lipid 2.5 g 0.4 g 3 Sacharride 76.8 g 77.5 g 4 Ash 1.2 g 0.5 g 5 Fiber 1.3 g 0.4 g 6 Calcium 41 mg 24 mg 7 Phosphorous 284 mg 147 mg 8 Iron 2.1 mg 0.4 mg 9 Magnesium 120 mg 50 mg 10 Vitamin B.sub.1 0.54 mg 0.12 mg 11 Vitamin B.sub.2 0.006 mg 0.003 mg 12 Nicotinic acid 5.0 mg 1.5 mg 13 Vitamin B.sub.0 1.0 mg 0.5 mg 14 Inositol 120 mg 10 mg 15 Choline 110 mg 60 mg 16 Benzoic acid 32 mg 14 mg 17 Vitamin K 10 mg 1 mg 18 Vitamin E 1.0 mg 0.2 mg
Because unpolished rice includes THE rice bran, it is difficult for water to permeate the unpolished rice, thereby requiring a special cooker such as a pressure cooker to boil unpolished rice. Furthermore, due to the rice bran, the unpolished rice is hard to chew and digestibility of the same is low.
Korean patent publication No. 91-7319 discloses a method of preparing polished rice which can be easily boiled. In the method, unpolished rice is dipped into water, the rice is then dehydrated and the dehydrated rice is cooked. The dipping and dehydrating steps are repeated. Thereafter, the resulting rice is dried using hot air. The drying step is repeated three times, with a first drying step being performed at a high temperature, a second drying step at a low temperature, and a third drying step at a high temperature. When using this method, cracks occur in the rice bran (pericarp and testa).
However, the method has disadvantages in that the method is only applied to treat unpolished rice and is not applied to treat rice grain. In addition, the entire process is very complicated and as a result of the cracks in the rice barn, the nutrient content of the unpolished rice is reduced and cracks of the thin rice bran do not easily occur according to the temperature. Finally, as the drying step is repeated, the unpolished rice is somewhat degraded such that the taste and external appearance thereof are deteriorated.
A method to solve these problems is disclosed in Korean patent application No. 95-10199. In the method, rice grain or unpolished rice is dipped into water to germinate and the germinated rice is allowed to stand at a low temperature for a few days and the resulting rice is cooked to expend an endosperm. The hull at the rice grains is cracked as the rice is expanded. Thereafter, the cooked rice or unpolished rice is dried at room temperature to harden the endosperm. The dried rice is fed into a sheller having two rubber rollers, thereby removing the hull and cracking the rice bran.
However, only 60 to 70% of the hull is removed. To increase this, the removing step is repeated, and the rice is aged with steam and rolled. Furthermore, the aged and unpolished rice should be dried to a level of 20 to 23% moisture content in order to protect adherence thereof on a roller. Due to this step, the gelatinated endosperm comes to have elastic properties and thus the unpolished rice thinned by rolling, thickens again. Therefore, it is difficult to boil the rice, with the time required for boiling being extended.